Meiosis is a two-step cell division process that produces four haploid gamete cells from one initial diploid cell. In the first division, the diploid cell undergoes normal mitosis to produce two daughter cells. In the second division, the two daughter cells each split again to produce four haploid gamete cells such as sperm or egg cells. These gamete cells have half the number of chromosomes of the original cell and can fuse during fertilization to form a new diploid organism.

1. Meiosis

2. Meiosis
• The process of Meiosis has TWO divisions
• In the end of the FIRST division, one cell
divides into two
• In the SECOND division, two cells divide into
four
• So you start with 1 cell and the end result is 4
cells!

3. Gamete Cells
• The second division in meiosis produces
gamete cells
• Gamete cells are sex cells
• These cells have HALF of the number of
chromosomes the original cell had

4. Haploid/Diploid
• The original cell at the beginning of Meiosis is
a diploid cell
• Di- means TWO
• Diploid cells have 2 sets of chromosomes
• Haploid cells only have 1 set
• The result of meiosis is 4 HAPLOID CELLS
• These haploid cells are used in reproduction

5. Meiosis – FIRST DIVISION
• In phase 1 (prophase 1) – chromosomes (each
consist of 2 chromatids) condense
– crossing over can occur
• In phase 2 (metaphase 1) – homologous
chromosomes align in the center of the cell
• In phase 3 (anaphase 1) – chromosomes
separate with sister chromatids still together
• In phase 4 (telophase 1) – cell pinches into
two cells each containing 1 chromosome of
the homologous pair

6. http://www-bcf.usc.edu/~forsburg/meiosis.html

7. Meiosis – SECOND DIVISION
• In phase 1 (prophase 2) – chromosomes
condense
• In phase 2 (metaphase 2) – chromosomes line
up in the center of the cell
• In phase 3 (anaphase 2) – sister chromatids
separate and move to opposite ends of the
cells
• In phase 4 (telophase 2) – two cells pinch into
4 cells

8. Adapted from http://www-bcf.usc.edu/~forsburg/meiosis.html

9. Taken from http://www.infovisual.info/01/021_en.html
Take a look at the both stages together